The present invention relates to a system for cooling a downstream cavity of a centrifugal compressor impeller in a turbomachine such as in particular a turbojet, an airplane turboprop or a gas generator.
The cavity which is formed downstream of the rotor or impeller of a centrifugal compressor in a turbomachine must be ventilated to discharge the thermal energy afforded by the impeller. This ventilation is generally done by bleeding off air at the outlet of the compressor, at the junction with the inlet of an annular diffuser which feeds a combustion chamber.
However, as this ventilation air is bled off at the outlet of the compressor, its temperature is already relatively high. It is further increased by viscous friction on the downstream face of the impeller, so that this face may be raised to a high temperature capable of attaining and exceeding the maximum temperature allowed by the material of the impeller, with a risk of deterioration of the impeller.